Red Dwarfs Will Be Here After Every Other Star Has Been Snuffed Out

Compared to other stars, red dwarfs are tiny and dim. But they make up for their unimpressive stature with their amazingly long lifespans, which stretch for trillions of years. Given that the universe is a mere 13.8 billion years old, it's unsurprising that there isn't a single known red dwarf that has entered the later stages of its life.

Why They're Like This

Red dwarfs form just like other stars: out of a rotating cloud of gas and dust brought together via gravity and that reaches temperatures hot enough to fuse elements. But these stars are less than half as massive as our own sun—sometimes as little as 7.5 percent as massive—and as a result, burn much cooler and shine less brightly.

That low temperature may seem like a setback for a star, but it's the key to a red dwarf's longevity. It means that they don't burn through hydrogen that quickly, and burning through hydrogen is what will kill a star. So while stars like our sun might survive for around 10 billion years, red dwarfs have the potential to live out their days over trillions of years. Once their time is up, they'll become white dwarfs, but because our universe is only 13.8 billion years old, that hasn't happened yet.

Why It's Important

Scientists long thought that planets around red dwarfs could never sustain life, since the stars' low temperature would mean life-sustaining planets would need to be extra close, thereby putting them in range of deadly radiation. But new research suggests this isn't the case—planets around red dwarfs could indeed be habitable. Since red dwarfs are the most common stars in space, this multiplies our chances for finding alien life. Learn more about these tiny space Methuselahs in the videos below.

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Written by Curiosity Staff February 22, 2016

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